The invention relates to methods for administering biologically active substances, and biodegradable compositions for administering these substances.
The rapid advances in the fields of genetic engineering and biotechnology have led to the development of an increasing number of proteins and peptides that are useful as pharmaceutical agents. The development of methods for administering these new pharmaceutical agents is thus gaining increasing importance. In particular, the local or systemic administration of biologically active substances, such as proteins, is a current concern.
The delivery of proteins can be complicated, as proteins will degrade in many of the carriers that have traditionally been used for the administration of small molecules. In many cases, the active forms of proteins are difficult to formulate in biodegradable polymers. Synthetic materials, such as biodegradable hydrogels, can be used to deliver proteins. In many methods, however, the delivery of the protein to the systemic and local circulation is relatively rapid, and is determined primarily by the rate of dissolution of the protein particles. These methods can be of limited utility, as drug release can occur in an initial "burst" rather than at a sustained, controlled rate.